So why bother with alternate weapons?

There are still many things about Maplestory I'd love to change. Even after Big Bang, speeds 4 and 5 still register as "Fast" when there is clearly a difference in attack speed.

As far as the choice between swords and axes - although this isn't fixed per say after Big Bang, the gap between swords and axes have closed considerably. Before, there were differences between swings and stabs. Now there is no difference. Before, Axes had lower mastery, now they have the same mastery as swords. Also before, Axes required completely different skill trees for Crusaders which locks you into using an inferior weapon type. Now they don't. Pretty much the only differences now between axes and swords are weapon speed and cost - with axes being considerably cheaper in base cost and scrolling costs. There are some axes which can compete with sword on attack speed so, considering the cheaper cost, it's much more worth it to use an axe over a sword.

There are other problems that plague axes though. Since so few users are axe users, shop owners don't want to take up a slot in their store for an axe no one will buy when they can put a sword in there that people will buy. So there are supply issues for axes as well.

I think you covered everything but range issues (are there any? I think I remember some ranges being shorter for alts) and universality of swords, but those are basically the same conclusions I'm reaching now. I don't like it that there's no big comeback for alts, but I'll take what I can get for now.